Submitted for publication December 13, 1996. Accepted for publication January 8, 1997. Supported by the American Society of Anesthesiologists, under the direction of James F. Arens, M.D., Chairman of the Ad-Hoc Committee on Practice Parameters. Approved by the House of Delegates, October 23, 1996. A list of the articles used to develop these Guidelines is available by writing to the American Society of Anesthesiologists.

Practice guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints.

Practice guidelines are not intended as standards or absolute requirements. The use of practice guidelines cannot guarantee any specific outcome. Practice guidelines are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice. The Guidelines provide basic recommendations that are supported by analysis of the current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data (appendix).

A. Definition of Chronic Pain

For these Guidelines, chronic pain is defined as persistent or episodic pain of a duration or intensity that adversely affects the function or well-being of the patient, attributable to any nonmalignant etiology. The Task Force has not given preference to literature based on any particular system of definition or classification of chronic pain.

B. Purpose of Guidelines for Chronic Pain Management

The purpose of these Guidelines is to 1) optimize pain control, recognizing that a pain-free state may not be achievable, 2) minimize adverse outcomes and costs, 3) enhance functional abilities and physical and psychological well-being, and 4) enhance the quality of life for patients with chronic pain.

C. Focus

These Guidelines focus on the knowledge base, skills, and range of interventions that are the essential elements of effective management of chronic pain and pain-related problems. The Guidelines recognize that the management of chronic pain occurs within the broader context of health care, including psychosocial function and quality of life.

The Guidelines recognize that all anesthesiologists may not have access to the same knowledge base, skills, or range of modalities. However, aspects of these Guidelines may be helpful to anesthesiologists who manage patients with chronic pain in a variety of practice settings.

The decision to implement a particular management approach should be based on a comprehensive assessment of the patient's overall health. The Guidelines recognize that accurate diagnosis and appropriate therapies used to modify the underlying causes of pain may improve analgesia and outcome. The risks and benefits of therapies designed to modify or correct the underlying cause(s) of pain is outside the scope of these Guidelines. Although headache is included in the definition of chronic pain, these Guidelines are not specifically intended for the management of headache. The literature search was not comprehensive with respect to headache, but the general principles of these Guidelines may be applied to the management of headache.

D. Application

These Guidelines are intended for use by anesthesiologists and health care personnel who deliver care under the direct supervision of anesthesiologists. The Guidelines do not compare the relative effectiveness of different interventions. They are not intended to provide treatment algorithms for specific pain syndromes. Complementary therapies are beyond the scope of these Guidelines.

Guidelines

I. A Comprehensive History and Physical Examination of the Patient with Chronic Pain

The literature suggests that a comprehensive history and physical examination be conducted. The Task Force and panel of consultants support the conduct of a comprehensive pain-related history and physical examination.

Recommendations: General Constructs. The Task Force identifies four fundamental issues that should guide a comprehensive history and physical examination of the patient with chronic pain.

1. The patient's general medical condition and extent of concurrent medical and surgical diagnoses.

2. Knowledge of chronic pain syndromes is a necessary prerequisite for conducting a chronic pain evaluation. Chronic pain syndromes may be related to pathology or dysfunction in one or more organ systems or to psychological conditions. In addition, knowledge of other medical or surgical conditions that may present with pain and may mimic chronic pain syndromes also is necessary.

3. Knowledge of the diagnosis and management of painful crises.

4. Knowledge of the diagnosis and management of medical emergencies and complications arising from the underlying cause or treatment.

Elements. The Task Force identifies five essential features of a comprehensive evaluation and treatment plan (Figure 1).

1. History. A complete pain history includes a general medical history with emphasis on the chronology and symptomatology of the presenting complaint. The data should include information about the onset, quality, intensity, distribution, duration, course and affective components of the pain, and details about exacerbating and relieving factors. Additional symptoms (e.g., motor, sensory, and autonomic changes) should be noted. Information regarding previous diagnostic tests, results of previous therapies, and current therapies should be reviewed by the anesthesiologist (Table 3).

2. Physical examination. The physical examination should include an appropriate, directed neurologic and musculoskeletal evaluation, with attention to other systems as indicated. Not only the cause(s) of the pain, but also the effects of the pain, such as physical deconditioning, should be evaluated and recorded.

3. Psychosocial evaluation. The psychosocial evaluation should include information about the presence of psychological symptoms (e.g., anxiety, depression, or anger), psychiatric disorders, personality traits or states, coping mechanisms, and the meaning of the pain. Evidence of family, vocational, or legal issues and involvement of rehabilitation agencies should be noted. The expectations of the patient, significant others, employer, attorney, and other agencies (e.g., Workers' compensation, Social Security Administration) also should be determined.

4. Impression and differential diagnosis. The previous findings should be used to determine the possible etiologies and effects of the pain (Table 4).

5. Treatment plan. Once a working diagnosis has been determined, a treatment plan is formulated with input from the patient, other involved professionals, and other involved persons (e.g., significant others or qualified rehabilitation counselors). Treatment and outcome goals should be discussed with the patient.

II. Diagnostic Evaluation

The literature is supportive of the conduct of a diagnostic evaluation for chronic pain. The panel of consultants and Task Force members also support diagnostic evaluation for purposes of determining potential etiologies of chronic pain and for identification of pain sites for treatment. The use of diagnostic local anesthetic blockade is suggested by the literature and supported by the Task Force.

Recommendations: Anesthesiologists treating chronic pain should have a working knowledge of the utility and interpretation of diagnostic evaluations, including diagnostic neural blockade, imaging modalities, pharmacodiagnosis, electrodiagnosis, and laboratory studies. Diagnostic evaluation is an essential addition to the history and physical examination in the evaluation of patients with chronic pain. The treatment plan, contingencies, and plan for reassessment should be formulated based on these sources of clinical data.

Neural blockade with local anesthetic, including somatic and autonomic blocks, may be useful in determining the site and etiology of chronic pain. Anesthesiologists have unique skills in this area that may benefit carefully selected patients. Anesthesiologists should personally review and interpret diagnostic data when clinically indicated.

III. Counseling and Coordination of Care

There is insufficient literature to suggest that the anesthesiologist's role in counseling and coordination of care is associated with improved analgesia or other health effects. The Task Force and consultants are supportive of the effectiveness of counseling and appropriate coordination of care in improving analgesia and quality of life.

Recommendations: Anesthesiologists should provide appropriate counseling of the patient regarding the pain syndrome diagnosis, treatment options, rehabilitation, and follow-up goals. In addition, the anesthesiologist should coordinate care with other health professionals, rehabilitation and vocational agencies, and social and legal entities. Longitudinal assessments of outcome should be maintained.

IV. Periodic Monitoring and Measurement of Clinical Outcomes

There is insufficient literature to evaluate the effectiveness of periodic pain assessment in chronic pain management. Multiple times of measurements, fluctuating patient and disease status, and variable interventions over time are confounding factors that make useful analysis difficult. The Task Force and consultants support the contention that periodic monitoring of the effects of therapy and patient status will result in improved pain management and reduced adverse health effects from therapy.

Recommendations: Accurate and complete records of pain therapies should be maintained. Reports of pain made by the patient should be the primary source of pain assessment (Figure 2) and should be obtained at periodic intervals. Periodic monitoring may include, but is not limited to, a patient's verbal report of treatment efficacy, other pain records (e.g., pain diaries), and reports of side effects associated with pain management. Analyses of aggregate outcomes are essential to continuous quality improvement of chronic pain management in the clinical setting.

For these Guidelines, multidisciplinary care includes, but is not limited to 1) contributions to patient pain care by more than one health care discipline, 2) a process or program of pain care by more than one health care discipline, or 3) a combination of 1 and 2.

The literature does not provide a standard definition for multidisciplinary care. The available literature was only sufficient to address multidisciplinary care on a programmatic basis. This literature is supportive of the efficacy of multidisciplinary programs in providing analgesia and improvement of health status (e.g., functional status, quality of life). The panel of consultants and Task Force members endorse multidisciplinary chronic pain management.

The literature, Task Force, and consultants also support programs that emphasize the reduction or elimination of pain medications as a primary objective of therapy (i.e., through use of physical therapy, biofeedback, behavior modification, or other psychosocial techniques).

Recommendations: Anesthesiologists offer a unique contribution to patient care in the context of multidisciplinary chronic pain management. Anesthesiologists should be involved in patient evaluation, provision and interpretation of diagnostic procedures, clinical pharmacology, provision of alternative drug delivery methods, provision of temporary or long-term neural blockade, and provision of neuromodulatory techniques.

VI. Multimodality Pain Management

For these Guidelines, multimodal therapy is defined as concomitant use of separate therapeutic interventions under the direction of a single practitioner to obtain additive beneficial effects or reduction of adverse effects. Examples include, but are not limited to 1) the use of neural blockade with medications, 2) rehabilitative therapies (e.g., physical therapy) with neural blockade or medications, and 3) medications of different categories (Table 5). The literature suggests that concomitant application of separate therapeutic interventions in chronic pain management provides effective analgesia. The literature on other health effects is equivocal. The panel of consultants and Task Force members also are supportive of the efficacy of multimodality techniques for the management of chronic pain.

Recommendations: Multiple modalities, such as the combined use of neural blockade, medications, or rehabilitative therapies should be considered when analgesia with acceptable adverse effects is no longer attained with single modalities. Ideally, each modality should be administered as appropriate to achieve the desired therapeutic effect. A multimodal approach may reduce the potential for adverse effects arising from either escalating frequency or dosage levels of a single modality.

The literature supports the use of antidepressants for reducing chronic pain without notable adverse effects. The literature also supports the use of antidepressants for providing overall health benefits and for improving mood. The literature supports the benefits of membrane stabilizing agents (i.e., anticonvulsants) and NSAIDs for providing analgesia but is equivocal regarding other health effects. The Task Force and consultants are supportive of the use of antidepressants, membrane stabilizing agents, and NSAIDs for providing analgesic and health benefits.

Recommendations: Antidepressants are useful medications for the reduction of pain and improvement of sleep. The specific agent and the dosage should be optimized for each patient. The beneficial and adverse effects should be monitored. NSAIDS and membrane stabilizing agents (e.g., anticonvulsants) also may be used for the reduction of pain. As with antidepressants, the specific agent and dosage should be optimized for each patient, with periodic monitoring of beneficial and undesirable health effects.

Recommendations: The adequacy of sympathetic blockade should be objectively assessed and recorded. Appropriate sympathetic blockade by the anesthesiologist should be provided within the context of the patient's overall treatment plan. To ensure the judicious use of sympathetic blockade, periodic monitoring should be conducted to assess analgesic benefit and adverse effects (e.g., sensory or motor block; failed blockade of sympathetic outflow, especially to the upper extremity; local anesthetic toxicity; site infections).

IX. Corticosteroid Injection Therapy

The literature suggests that locally injected corticosteroids are effective in providing analgesia. The literature is equivocal regarding other health effects. The panel of consultants support the importance of locally injected corticosteroids in improving analgesia and enhancing patient functioning and quality of life. The consultants are equivocal regarding the adverse effects of corticosteroids.

Recommendations: Local injection of corticosteroids by the anesthesiologist should be provided within the context of the patient's overall treatment plan. A directed neurologic evaluation should precede the local injection of corticosteroids. Appropriate follow-up evaluation is necessary to monitor health effects, including analgesia, function, and adverse effects on local tissues and the hypothalamic-pituitary-adrenal axis.

X. Neurostimulation Therapy

The literature is supportive of transcutaneous electrical nerve stimulation (TENS) and spinal cord stimulation (SCS) techniques in providing analgesia and is suggestive of the analgesic benefit of peripheral nerve stimulation (PNS) techniques. The literature is equivocal regarding the beneficial or adverse health effects of TENS, PNS, and SCS. The Task Force and panel of consultants are supportive of neurostimulation therapy for analgesia.

Recommendations: An office or home trial of TENS should be considered as an early management option because of its low complexity and low risk. TENS also may be considered as adjunctive therapy.

Peripheral nerve stimulation should be reserved for patients with a peripheral mononeuropathy who have responded to a diagnostic sequence of local neural blockade and a stimulation trial.

Spinal cord stimulation should not be a first-line treatment but may be considered after failure of oral medications. SCS may be effective in the management of patients with peripheral neuropathic pain or with pain arising from the spinal cord (e.g., arachnoiditis, syringomyelia, spinal cord injury, multiple sclerosis). It should be preceded by a trial with a percutaneous electrode system.

XI. Opioid Therapy

Opioid therapy for chronic pain management may be administered by several routes, the most common being systemic delivery (e.g., oral, transdermal, or intravenous). Opioids also may be delivered directly to the neuraxis (e.g., epidural, intrathecal). The relative merit of systemic versus neuraxial opioid administration for chronic pain management was not addressed in the these guidelines.

The literature supports the analgesic efficacy of systemic opioids. However, the literature suggests that systemic use of opioids may be associated with increased risk of adverse sequelae (e.g., tolerance, dependence, pruritus, nausea, and respiratory depression).

The literature suggests that neuraxial delivery of opioids for chronic pain is associated with effective analgesia and is equivocal regarding adverse effects. The consultants are supportive of the analgesic benefits of opioid therapies and are equivocal regarding adverse effects.

Recommendations: Opioid therapy may be considered when analgesia provided by other modalities (e.g., NSAIDs, TENS) is no longer adequate to manage chronic pain. Systemic or neuraxial opioids should be administered on the basis of patient need. Delivery of opioids should occur within the context of a logistic system that provides the resources and availability of personnel to respond to patient needs and according to applicable local, state, and federal regulations. The analgesic benefits of opioids should be balanced against the potential adverse sequelae of long-term opioid use. Patients treated with opioids for chronic pain may require frequent follow-up evaluation. A controlled substance agreement or a second opinion from another provider with expertise in pain management may be considered.

XII. Neuroablative Techniques

Neuroablative techniques destroy neural tissue using chemicals (e.g., alcohol or phenol) or thermal lesions (e.g., radiofrequency or cryoneurolysis). The literature suggests that chemical and thermal neuroablative techniques can provide some control of chronic pain and reduction in regional sympathetic overactivity. Severe adverse health effects from treatment are possible but reported rarely. There is insufficient literature regarding the value of prognostic neural blockade before neuroablative techniques. The Task Force and consultants are supportive of the value of neurolytic techniques in symptom management and are neutral regarding other health effects.

Recommendations: Neuroablation should be preceded by confirmation of needle placement using local anesthetic, imaging, or electrical stimulation. Successful temporary blockade does not guarantee the success of subsequent neuroablation. Although the reported incidence of adverse effects of neuroablative techniques is very low, the impact on the patient may be catastrophic. Reported adverse effects include motor, sensory, and autonomic dysfunction (e.g., paralysis, deafferentation pain, loss of sphincter control, or impotence), regeneration pain, and neuralgias. Neuroablative techniques should be used as part of a comprehensive approach to managing pain and applied only as a last resort after failure of other therapies. Follow-up assessments of pain and other health effects should be conducted periodically.

Appendix: Methods and Analyses

The scientific assessment of these Guidelines was based on the following statements, or evidence linkages. These linkages represent directional hypotheses about relationships between chronic pain, symptom management, and clinical outcomes.

Scientific evidence was derived from aggregated research literature, with meta-analyses used when appropriate, and from surveys, open presentations, and other consensus-oriented activities. For purposes of literature aggregation, potentially relevant clinical studies were identified via electronic and manual searches of the literature. The electronic search covered a 30-yr period from 1966 through 1995. The manual search covered a 52-yr period from 1944 through 1995. More than 3,000 citations were initially identified, yielding 1,450 nonoverlapping articles that addressed topics related to the 12 evidence linkages. After review of the articles, 1,074 studies did not provide direct evidence and were subsequently eliminated. A total of 376 articles (from 153 journals) contained direct linkage-related evidence.

A directional result for each study was initially determined by classifying the outcome as either supporting a linkage, refuting a linkage, or neutral. The results were then summarized to obtain a directional assessment of support for each linkage. The literature relating to five evidence linkages contained enough studies with well-defined experimental designs and statistical information to conduct formal meta-analyses. These five linkages were linkage 2 (diagnostic evaluation), 5a (multidisciplinary pain management programs), 5b (multidisciplinary pain management programs that emphasize the reduction or elimination of pain medications as a primary objective of therapy), 7a (antidepressants), and 7b (anticonvulsants and NSAIDS), 10a (TENS), 10b (SCS), and 11b (opioid therapy, systemic drug delivery).

The following terms were used in the Guidelines to express the strength of the evidence relating to various interventions and their associated outcomes.

1) Insufficient data: there are insufficient published data to provide an indication of the relationship between the intervention and outcome.

2) Suggestive data: there is qualitative evidence in the form of case reports or descriptive studies, but there is insufficient quantitative evidence to establish a statistical relationship between intervention and outcome.

Combined probability tests were applied to continuous data, and an odd-ratio procedure was applied to dichotomous study results. Two combined probability tests were used as follows: 1) The Fisher Combined Test, producing chi-square values based on logarithmic transformations of the reported P values from the independent studies, and 2) the Stouffer Combined Test, providing weighted representation of the studies by weighting each of the standard normal deviates by the size of the sample. A procedure based on the Mantel-Haenszel method for combining study results using 2 x 2 tables was available for use with outcome frequency information. An acceptable significance level was set at P < 0.01 (one-tailed), and effect size estimates were calculated. Interobserver agreement was established through assessment of interrater reliability testing. Tests for heterogeneity of the independent samples were conducted to assure consistency among the study results. To control for potential publishing bias, a “fail-safe N” value was calculated for each combined probability test. No search for unpublished studies was conducted, and no reliability tests for locating research results were done.

Tests for heterogeneity of statistical tests and effect size were non-significant for linkages 2, 10a, and 10b, indicating that the pooled studies provided common estimates of significance and population effect sizes. Tests for heterogeneity of statistical tests were significant for linkages 5a (health effects) and 5b (analgesia and health effects). Tests for heterogeneity of effect size were significant for linkages 5a (health effects), 5b (analgesia and health effects), 7a (analgesia), 7b (analgesia), and 11b (analgesia). Significant findings for analgesic efficacy for linkage 11b may reflect the small number of studies used in the pooled analysis (N = 5). Significant findings for analgesic efficacy of 7a and 7b may reflect either the differential influence of the various adjuvant medications or that the pooled analysis used adjuvant medications whose primary purpose was not specifically intended for pain management. Significant findings for linkages 5a and 5b suggest that the findings be further examined for commonalities in therapeutic approaches, medications, personnel, or targeted patient populations in multidisciplinary pain programs.

The findings of the literature analyses were supplemented by the opinions of Task Force members and by surveys of the opinions of a panel of consultants with expertise in chronic pain management (N = 96). The rate of return was 60%(N = 58 of 96). The percentage of consultants supporting each linkage is reported in Table 2. Consultants, in general, were highly supportive of the linkages (i.e., a] agreed that they provided analgesic benefit, b] reduced risk of adverse outcomes, c] improved function and quality of life, and d] were important issues for the Guidelines to address).

The feasibility of implementing these Guidelines into clinical practice was assessed by an opinion survey of the chronic pain consultant panel. The rate of return was 54%(N = 51). The mean number of patients treated annually by the consultants was reported to be 1,636 (min/max = 10 - 9.000). Responses for feasibility of implementation of the Guidelines were as follows: 96%(N = 50) of these consultants indicated that implementation of the Guidelines would not result in the need to purchase new equipment, supplies, or pharmaceuticals. The two respondents who stated that purchases would be required estimated cost of initial implementation of the Guidelines to be $20,000–30,000 for the purchase of improved nerve stimulators, cryotherapy, and radiofrequency equipment.

Ninety-two percent of the respondents indicated that the Guidelines would have no effect on the time spent on a typical case. None reported that the Guidelines would reduce the amount of time spent per case. For all respondents, the mean increase in the amount of time spent on a typical case was 2.1 min. Of the 8% of respondents who reported an anticipated increase in time spent on a typical case, the mean was 18.0 min (range, 4–60 min).*

*Readers with special interest in the statistical analyses used in establishing these Guidelines can receive further information by writing to: Peter R. Wilson, MBBS, PhD, Anesthesia Department, Mayo Clinic, 200 First Street, Rochester, Minnesota 55905.